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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '240212d73622dfed1b4b6cbb08b07dcfc2742abdb3a0a4b0919bb74133b14744' 
  AND token = 'v1mQHl+VgYzGd0GtZWetfj0fa6/jXW46HuJvYkDZutc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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