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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd99c7eb9d4a4f4fe6f29701df08ed7490efc4d38230c6e7530cd215f78d15af9' 
  AND token = 'LttqtrPf6WRIxIKBq39I7+VmC68WgsEJONlLTQQv33I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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