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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c19e4656e832080f589fa32bc38e32ce3059a5b8c2c4f19ac866cbb73452f519' 
  AND token = '9WVbg2QrhSq0z9Ju2ZLR5yu0qLMk8eZrdfSlfoQ60/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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