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SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'd1b6fe918f8fd0bc836075b9cdac9ff9b5e3d619be1f3f1eccee258fb642dab2' 
  AND token = 'N+TdGT9+dbTPn0HUNZIIbZM5NW6CnFrAx4ZnmsOYlNo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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