SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f3af8fa958f0693b3cc2dd113bf4011be7c6681f5a105c04738491c5d0ae870' 
  AND token = 'LL/Jp8t11WJwH56+aohgmMYcawxrE96uPqPEIxfR4oo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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