SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f97d6b7885d4d3340f40863506248761046bf12c2cb8c44b4fd3831f50018b73' 
  AND token = 'gCmuKZhbDpIxdU85jX+lop8YKLU8nw5XCPCF8ByL3Lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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