SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a739340f8c9553fda9e66c4d5704a02593a5f7b6f5928a18a79e2604d888d92' 
  AND token = 'vvntEV2/5n3vdvFKTkSHiSK7WnDhIvWu/haScL4GMUg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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