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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b47f7f3d97b2ff5d74e79baee9a817fa3351ba0c4719bab7e0ad7a2418b0d216' 
  AND token = 'TgK4M/jS6LVo+2C4dp0QaR0ng07WqCWcSbSYTpx6RAE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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