SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '400476f2b3edd4a88f5a1519a587db08341bdceac52245df7ab3808ac9b094a5' 
  AND token = 'ITK7H7z6W7iAH2spmlmzhLFzogr3FIFPLeLMLRstgeg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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