SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '190a17e5e71842be912c00bbbb69652b3e430df82be8f857ed55649b29cc9a92' 
  AND token = '8LU3GWeJXFSFKOqjPCO5K3O5fkxDz4jpZDtgLn/nk0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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