SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b545d295ff843ff16d72a6a421ee27bfb6676bd84ad0bac6a32e49c894205737' 
  AND token = 'b/nDJRamVrvCRJxCiQEjzivkRWCVgKC3bw/Zrf4Dk6M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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