SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b7696a7c0bf3f8285906b1c97784e54208fafbec245071d0d743d5a99f39f2f8' 
  AND token = '2zYv1CLjIihhmkebt9BwNrfdAoF1/AdRW2/g9cZQDGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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