SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4b429694d0afcc80723a578c2875e9f0d7f23bc39d420b92c45d83450db51f86' 
  AND token = 'hbFKNhMUFYhHFFC15aDlgY7/RtXJoeHl6LSdU2+sktw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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