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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '03c03e885c9d0be76a781478b03aff780db339fee3e682808592a5a2de50313a' 
  AND token = 'j+MVayUoECRTZk6Jlya1BJmXe1RTSHM4Y+Rj4fnvHr0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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