SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21ff13e9871726a61476e2be49f0cb2f43578d2cc9ea3d61c0825b854601227a' 
  AND token = 'a0sme4XMGNLVSDNwb1ZS0Q6IyhjKYfBEoemoWcnXmfs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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