SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b9fc2372ac844749d0c1de5029439f8cf7fd795330321196966ee2f7c7cb621' 
  AND token = 'Web2mSfho/S+E/TnVzw6B0ObrS41kMTshh1lCMcnqBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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