SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5cdde0c189643f8c0795fbdcf76db98b4368264f63b91b6ae7a18abb0220d6e2' 
  AND token = 'I1bUwiTrJmMnAoT86Rm71EpTOcvyl6UQwo8CnSDtpw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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