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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '98be81b2a46ce35b293ff12be6d42a93c6c577837aa9beb8ad7b58bf7978cae1' 
  AND token = 'CNDzSdN23Ceenz94VjHsqEkg8QHpBBt/Gb1NfknNszY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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