SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '54285de23b5d5a4b9fe033e913aaf82889c5ccfe7fbac40359a286e268bb101b' 
  AND token = '6SnzLPyZ3IwHjPdPJ1F1leuHwzhlulTSm5Cbv2x3Ffg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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