SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '942adc6cb1ed8a8b4a82fb03122e789748da48af62216acdd252ec5f91282454' 
  AND token = '49fYCkM8g08R+9krJEWuV3yj4V8Jz4iOJJ2AGfHjCBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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