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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'bb9a1c6b994ffe6001c4284cd7f3ff5d82c1b097991d2b22f90dcbf1948a0ca1' 
  AND token = '0qQVm+ErzM+1SWRiMpMyRRpIoTW2KGjT913VYbeMdyo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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