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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe7946b50ca1d0a0051d2c8037c646112bfa452aad7f0bf0b4d0747a9bee5d22' 
  AND token = 'VvhLMXyXLBKSWrh2YQ75C04Kg1DNKmc9R3BgDiW8ltQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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