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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e516dd17d2f776af36d69b00ff1a130c2a3ce13a6aad39aa2600683d1a7bc894' 
  AND token = 'ljA4ZUt46P1tTf/LC9mo4tJVjYc/xBkeTzyBdqaEMNQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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