SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e96614b7819ea0415e368da8ffda940a534274dbf93d8883526cd3bc3705bcd' 
  AND token = 'r4KIGiFJihLB/JDFKakgrPTv29XfbXbpjds2rZgLg3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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