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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6a626c84539162b9a8530b7fd9c34edd4eb676b411f3f7b0b02a5b0647c0e855' 
  AND token = 'kuEtx6dXZAHegEoRvec+2PcJsi6M99FaDKMTEdecVUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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