SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d84c578875e26e44fa3e9937f0a17904b3f4f4f50ee043cc1bc86587fa16c5a' 
  AND token = 'ydMsw1uTby/9FGe1wmTmVgoKKOPLsrGSShV+nXjgyz8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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