SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57e2ea0d391bd158f8b443793c6ef338cde067913787736f6e5b81054f2c4e68' 
  AND token = 'vORBWPyNFEFMFCmjD3pM7NayF+2NZB19sddvMO/Aa6o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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