SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4020a9939bc637e0e8422e5749d6c172e35543362b608c66e49544fc528bf0d7' 
  AND token = 'USeZ/na91k3Kp+XARlKA5OgK2kEMbMCWJ2DldWTdi5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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