SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '391a76eaea88d028e7bba807c7972d5b4d76141eb230fb3734944c791f5bdaea' 
  AND token = 'Ks+jyPStr/t2P8c+qnkO2npwzRLOKHpU9X2AunGqYng=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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