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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6e9f5305c2497e0ee76b8309f26ff6887cd94922e5ceaf1639a00a38b9c3cdc' 
  AND token = 'Lkm6NXR0Dsoq1bvAr8wWajA0thHhs+lM4BYxxfmscpU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}