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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'befa7e55d9e5ba8bc9ffe1f05e721ec9e60cba10672f60fc70a3287feacad68e' 
  AND token = 'tVkQmcjhmskkOlpUBR2X+p6ZOkRVJcGvl4PFO43ehgI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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