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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd68c1ef1111d2e1eff013a41d4065b4fb6c52fa2e217409aa91d2bedad628b9' 
  AND token = 'vQZiVnxj9KlI/bh+H4u988ugjjtbMUrKFh/0PxDo/Bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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