SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8234bf4acbf7628478efb5a93e99064dc45a15b3e8b680baed74d4fad7107d13' 
  AND token = 'MjJazIklkjHJP+egxhXJdk1X2gp/LqB5SbOng/ErmUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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