SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90167235b7cd466dffa77ed2784a291e6e6bfbbedca69a2c74c80ab4b8f7c291' 
  AND token = 'yjKpsUPrPvK2GGxBXUPdlNZ3vLZ/1zFWK07hB9RZJRM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00061

JSON explain

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