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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '8b6e4bdf61442bc1cb2bf86bb746b583d6685b90502c941d3a97cdd20d1e5f88' 
  AND token = 'cebgrMIepx2AGs36PyXgQjvaLRuqpd1Mp5NSIIAGT4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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