SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbcd91fbd0960b3229e5627299aa16aacb0a750156e1a8978eacd83ecb80365e' 
  AND token = 'WJe+6rOtCWnHwECyeOSg4/v+VfOjvwVrj5vcxMjPfHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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