SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35a7cb6f282ce3b272565eca491d38c71b752c4780627f874ac39db530c2f051' 
  AND token = 'gSFTGJ/jcBCTHjhzIEuTYILTawpOs35ephz7L6k60fM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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