SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '280a65fb0d2055990edb3992bb349d02b3f534f5fc04024f226c4ca2efcb17ac' 
  AND token = 'MkEgies+1w/lXJ7/tqYz7vXUx5yrxrPQvdnlGnLlKPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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