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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'b80f50610dc6a79d59ef17463aae4eb9d80fc62e5884bfa7aa5507644a5767ff' 
  AND token = 'U5sOiBkWEpLmb7Rg86bJtqmjrERDLEVAJEp+Y8Cqsoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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