SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ebfa977ec245993614d6356797b0781909123f8a8d1319bbb512811ca77c9ae' 
  AND token = '3szHadjxRR1o5AmQnPAhzPOr1Opc/KYurxI21vjtEbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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