SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75f3b125479b8f067341e603c20d3b91a31eb933382c7464585c3054b638046d' 
  AND token = 'mjl0dPX15MiAqXL7Pa+uIv6Pq+qa79RhYmLJc4cK/Qw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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