SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ab3ebcf91929f6a3d3063655c59b37b91a31cdaae34f63da56d4363a6f92e48d' 
  AND token = 'FLhXrGdwUqDdVMef/yR4SUfbDsSNveCOQ0Ujm5mfmHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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