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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e031bab7adf5d96b3fb37968f026adec323b4444e1e9870c54d46ff5acfc9f39' 
  AND token = 'fU9Do7dp9M7dmf7l7nkKKd7VyvSQ0b+wo9NZUpzUDZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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