SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b71750316be1986ee29d2730093511ea35e95766f972ed24b043619c008a1721' 
  AND token = 'FwBcj9ngHp5ghrVu9uzCfPTO+0N8f0LuylZZpzkHRK4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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