SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49e5edc20ab4fa4a8bd357937bdab86655cd8c21e246ee619227b8de4bd9fac6' 
  AND token = '6CqdnS2J7rRiVC0qW1VDMUoLIRDMGKHVbGpnqO8M9ns=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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