SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae2fc5cb2efeed19886ce583072c4c4fe48c209f747f885cec0ad1e1a07defb6' 
  AND token = 'sJRmF2KehknM8DyvdYO50zybcQDe+uBXiAeiPbx7SIM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00057

JSON explain

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