SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a09467bac078c8242838429205daea41a1c3d21b706753a6390f806b8bf1aca3' 
  AND token = '9CgpgyrsOXA5CfESm88wKOsUAyfwzUgzUybagHOmuR4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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