SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c2d5333fcc648de219c21db9fe968996ff6069b42cf8d16bdf78a465ac6adf4' 
  AND token = 'c5jwnCXznEm5wX14K8j7PSCK5JqpRgq5AHbOzLAGHpg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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