SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '276e702ef16a092cfb82852fb2bd5de1e249790715e77c1d53b8e5ccfeebaff0' 
  AND token = '4X5upFdIFidMKdHw1iLmDhCyLQpFRBP8cXvnWDehnWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00079

JSON explain

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