SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e398c676839a396f678ba157d38a351a6c2a51737223a189764235b1e4e9386a' 
  AND token = 'PTcViKIgxBPKnleTKNT7Gif7xJmsNwsozNQwm4fNTLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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