SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c94759a20e3a4006f98e726e3bfffbc748b0147aea3bb155106e17c91705bf4b' 
  AND token = '5A80EDp5ACg25KkQnSR8kTvQ5TCKs7yCvdrCu9uc+Xw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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