SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '312eaf63624cbadf264d15d2c9aad377473b1a29d09b2d92825d2dba1fbbffff' 
  AND token = 's4XuQPmMRySLIMR/rUP2CPOIS+2yvCUsQdK15GwLcuQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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