SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '575bcf1b7af825dbcde94c98a71caf7af36699235541810300ecdb0471c7c55c' 
  AND token = 'su+N0BF5Aim2fDgJY8LRQBzqxAyyW3MFZBAE3BSijVg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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