SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e751b11072938629d9924ca84dc577c90de6a70fa8a57e1b98c03282416b7eca' 
  AND token = 'F90hqeJWGnPlU2sTgmKusxZRALHNEfP8uCT18xXLDqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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