SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d7335aa508d3e776973f3100103570a4b14b832e0be2a16f523d2badf07f78a' 
  AND token = 'hcQqqKISdZOFWBb/bym/cYCuRtjSCLdmbu/2RIMrDGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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