SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '68b7895a8bb83db71e6f0e14eb976e04aa90a0f20cd5d6e336fe2940badc8f61' 
  AND token = '7lTpwNLfu2Q7GZIh+25MjwJACNRNOUBBYxjRCUeiUSg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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