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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e991d1267841ebfa072124560e37c197d995d1f4b01c916fce1a968dc64b35e3' 
  AND token = 'CSk67yfhF/e0npI5Yj8BBhLKEVZmgd7jfOKMvExT9eI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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