SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bfa4665f50947280d93ce7403445e3705018d984636f7e4f32a5abfee4a4b6ca' 
  AND token = 'y3qmmYG3scZnmhc/M7ZXzrwybMIA7AOddiWofB1GE8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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