SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b87dfb619daffc515bbfa5ffdca714f408c7deedb416bcba70fe6ef039d50bf6' 
  AND token = 'tDV8KvVPzYqR/PwiYOZ8bMuTIWHLhsALSySbqbS/7f4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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