SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '34c1ac0379441505ada6a0aef3377d68a3f47cbfa63ba8fe2554b01aab375d65' 
  AND token = '72HxVNkzzDli3sLACm0ifLQVGPj1MoAArZHLDvDjukM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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