SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c8c6552bfa06013600718f0ba3258e723e3269a2f67fc53dcd69a5033f2274d' 
  AND token = 'UYsf/7rNWMAexMK7mipnV1GrTIFWdsU7pKlM6cdJiuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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