SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7fda17d0d809dde98e865b375fac6e587c0a8f47051fc196f9337d89179cea4' 
  AND token = 'zqc5ehFlxfOFVp0BiXIKc8BgEp9aN2ETtoj3ZMb8rFM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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