SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f68cb07fb0d9993d59731aba33e6cfce84ed90a3b69f3a8bd638e26f6ff8d5cb' 
  AND token = '0QV13qkjX1+lUjzSwhtLhMj4XNi1M/uLJdlZaqWgmhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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