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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5bfe4942bc41fc30b3a903cb06d394509c56d3b7b4e9ada4b5fa610a11c455dd' 
  AND token = '8heb3f6wyGb/hjRSVTrySnHBWktp/sJcejMqqxOHJMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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