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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6bf862b615f2780037c01d3867117e6ebb8365c743240af2c510f783e01f833' 
  AND token = '8Dujzr0sM7w18+Wg2447SH44iKVG9ID2zbzIhiQIK9k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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