SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c4b46aee014bb3831dacdd3ff985c924236d5913a31521f3011fea308878f6e5' 
  AND token = 'yNFpbGRbbqNSucCNYv9dGRRmvAiSw9BJJdNPkQlfaE8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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