SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c7a17b547ba8fe8808136490be9ea161f315204a75269f850d1420f1f54a67' 
  AND token = '/jcPR1uRJjEXygettopT3TRIAUnKD3zMn61cYzrLVdI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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