SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52e674e9fd49f18e3c46b5fcf466af721714e8900dd0f3b96fe8607f490dda39' 
  AND token = 'y8Tup/ml2CRtgkArFaI36eIVTAJnThjjcisHSerLIow=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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