SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0a874c578ed978e0518fff9334033723971542131ed023f20aad3b3869fed7d2' 
  AND token = 'yEgfiEiPauT613y4PvObDMnfpgKx7329oC15cHGVc3U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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